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 ###Instrução: Quantos prefeitos municipais diferentes houve no município com uma área de 42,66 km2?
 ###Tabelas: CREATE TABLE administered_by_independent_administrative_institutions (administered_by_independent_administrative_institutions_id AUTO_INCREMENT PRIMARY KEY, English Name VARCHAR, Japanese orthography VARCHAR, Pronouciation VARCHAR, abbreviation VARCHAR, Provider(IAI) VARCHAR, Foundation INT) CREATE TABLE table_presidential_elections (table_presidential_elections_id AUTO_INCREMENT PRIMARY KEY, Election VARCHAR, Candidate VARCHAR, Number of votes VARCHAR, Share of votes VARCHAR, Outcome of election VARCHAR) CREATE TABLE house_of_oldenburg (house_of_oldenburg_id AUTO_INCREMENT PRIMARY KEY, Birth VARCHAR, Marriage VARCHAR, Became Consort VARCHAR, Ceased to be Consort VARCHAR, Death VARCHAR, Spouse VARCHAR) CREATE TABLE municipalities (municipalities_id AUTO_INCREMENT PRIMARY KEY, Municipality VARCHAR, Type VARCHAR, District VARCHAR, Area (km²) VARCHAR, Population (2010) INT, Pop. Density (per km²) VARCHAR, No. of Barangays INT, Municipal Mayor VARCHAR) CREATE TABLE verified_aerial_victories (verified_aerial_victories_id AUTO_INCREMENT PRIMARY KEY, Number INT, Time INT, Aircraft VARCHAR, Opponent VARCHAR, Location VARCHAR)  
SELECT COUNT Municipal Mayor FROM municipalities WHERE Area (km²) = 42.66